Doppler Aided Tracking Loops for SRGPS Integrity Monitoring

D. Gebre-Egziabher, A. Razavi, P. Enge, J. Gautier, D. Akos, S. Pullen, B. Pervan

Abstract:	This paper evaluates the potential benefit of using Doppler aided carrier tracking loops as part of the JPALS integrity monitoring scheme. It is envisioned that Doppler aided carrier tracking loops will be used as part of the radio frequency spatial environment estimator. Using a frequency domain performance analysis of a third order Costas loop the contributions to the total phase error from local oscillator instability, satellite clock error, platform dynamic stress and platform vibration are quantified. The benefit of Doppler aiding to mitigate phase errors due to platform dynamic stress is quantified. The performance analysis shows that without external Doppler aiding the minimum carrier to-noise ratio (C/N0) that can be tracked is approximately 26 dB-Hz. The achievable tracking loop noise bandwidth at this C/N0 is approximately 10 Hz. Removing platform dynamics using an estimate of carrier Doppler provides an approximately 5 dB-Hz margin allowing signals with C/N0 as low as 21 dB-Hz to be tracked. This is achieved by narrowing the carrier loop noise bandwidth to 1 Hz. Some of the error models and analysis results are confirmed by postprocessing experimental data. Finally, the implications of these results on JPALS integrity monitoring are discussed.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	2562 - 2571
Cite this article:	Gebre-Egziabher, D., Razavi, A., Enge, P., Gautier, J., Akos, D., Pullen, S., Pervan, B., "Doppler Aided Tracking Loops for SRGPS Integrity Monitoring," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 2562-2571.
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